Crank-case-venting means for pneumatic tools



July 6,1926. 1,591,540

A. LEVEDAHL ET AL v CRANK CASE VEN'I'ING MEANS FOR PNEUMATIC TOOLS Filed Nov. 8, 1923 Patented July 6, 1926.

UNITED STATES 1,591,540 PATENT OFFICE.

AXEL LEVEDAHL AND REINHOLD A. NORLING, OF AURORA, ILLINOIS, ASSIGNOBS TO INDEPENDENT PNEUMATIC 'IOOL COMPANY, OF CHICAGO, ILLINOIS, A CORPORA- 'IION OF DELAWARE.

CRANK-CASE-VENTING MEANS FOR PNEUMATIC TOOLS. I

Application filed November 8,1928. Serial No. 678,470.

This invention relates to air venting means for crank cases of portable piston actuated pneumatic drills and like tools.

The invention has articular reference to that type of air ventin means wherein the valve device is opened centrifugal forces set up on the rotation of the crank shaft to allow the escape of air pressure from the crank case, without leakage of lubricant therefrom through the venting means regardless of the position of the tool, as disclosed and claimed in our copending applications Serial Nos. 673,469, and 673,471,both filed on November 8-, 1923.

The present invention provides a form of such means adapted for crank shafts having counterweights formed integral therewith.

The invention consists further in the matters hereinafter described and more particularly set forth in the appended claims.

In the accompanying drawings- Fig. 1 is a side view of a portable piston actuated pneumatic drill having incorporated therein an air venting means of our invention;

Fig. 2 is an enlarged fragmentary vertical sectional view through the upper end of the crank case and crank shaft to show in detail the air venting structure;

Fig. 3 is a top plan view of the cap of said structure; and

Fig. 4 is a plan view of the counterweight carrying the valve device of the vent.

Fig. 1 shows a portable pneumatic tool of the type to which, our invention is particularly applicable. As shown, the tool has an outer case 1 carryin on one side a handle 2 and on the other si e. a combined handle and throttle valve 3, throu h which compressed air or other motive f? to the tool for operating it. The spindle chuck 4 at the lower end ofthe tool carries a twist drill 5. At the upper end of the tool there is a' screw feed '6, as usual in tools of this general character. The case 1 is pro vided on each side with a pair of cylinders 7 7 only one pair being shown in the drawings. The cylinders of the tool are arranged V-type and in them work single-acting pistons 8 connected b connecting rods 8 to a' crank shaft 9, as s own in'Fig. 2.

Considering the tool in an upright osition drilling downward, the parts wil be as in Figs. 1 and 2. At this time the crank uid is supplied he upper end 10 of the crank shaft 9 is V made hollow or drilled out to provide a central bore or passage 14 opening outward through the upper end of the crank journal 10, as shown in Fig. 2. The lower end of the bore 1 1 communicates with a passage 15 drilled or otherwise formed in the counterweight 16, with which the crank shaft is integrally provided. The passage 15 is preferably made at an angleto the crank journal 10, namely, at approximately as shown. Riveted or otherwise rigidly secured to the inner face of the counterwei ht 16 over the passage 15 is a tubular mem r 17. This has a flat base 18 riveted or otherwise rigidly secured to the inner face of the counterweight 16 at the passage 15. The member 17 has its tubular portion 19 aligned with the inclined passage-15 and in communication therewith through a hole 20 in the base piece 18. The passage through the tube 19- is restricted, as at21, thereby forming a seat for a ball valve 22. When off the seat the valve 22 is held from moving out of the outer 0 en end of the tube 17 by is; stop pin 23 insi e of the tube and carried y it.

Closing the outer end of the projection 12 I is a cap 24 provided with an internal annular'shoulder 25 to seat a ainst a dish shaped plate 26 applied over t e outer end of the crank journal 10 and its bearing 11 so as to form an end thrust plate therefor. The shoulder 25 also spaces the top of the cap from the plate 26 to rovide an airreceiving chamber open to tide atmosphere through one or more outlet port holes 27 in the cap 24, as shown in Figs. 2 and 3. The outer edge of the plate'26 is enlarged .to provide an inwardly facing annular shoulder 26 to engage over the outer sleeve 11 of the hearing to hold the plate 26 from displacement thereon.

The late 26 is apertured in 'its center to receive a tube 28 attached to the plate permanently, as by having the edge of the plate around the aperture engaged in a groove 29 between annular ribs or flanges on the tube. Said tube 28 extends down into the bore 14 in the upper crank journal 10 and terminates adjacent the lower end of said bore, as shown in Fig. 2. A strip of packing 30 is between the crank journal 10 and the tube 28.

In tools of the character to which our invention particularly relates, the pistons 8 are single-acting and the cylinders 7 open at their inner ends into the crank cases 13, and moreover the inner end of the valve mechanisms open into the gear cases and compressed air, used in operating the tools, leaks into the crank cases past the pistons and valves. By our structure, an accumulation of air pressure in the crank case 13 to do harm is avoided. In use, the drill may be held in various Working positions, depending on the lay of the work. When the drill is held in the position shown in Figs. 1 and 2, the end journal 10 is uppermost and the drill bit 5 and the vent tube 17 both extend downward with the stop pin 23 below the ball valve 22. In this position, when the drill is idle, the ball valve 22 will automatically unseat and come to rest against the stop pin 23 by the force of gravity. When the drill is operated in this position, centrifugal forces which are set up by the rotation of the crank shaft 9 will also cooperate to retain the valve 22in its unseated position and allow for venting of the crank case through the tube 17, passages 15 and 14 in the counter-weight and shaft, respectively, and the outlet ports 27 in the cap 24.

When the tool is held in its inverted position, that is, with the end journal 10 lowermost, the drill bit 5 and the tube 17 will both point upward. In this position, the ball valve 22 will, when the drill is idle, automatically seat itself and close the vent by the force of gravity. 'When the tool, however, is operated in this inverted position, centrifugal forces which are set up by rotation of the crank shaft 9 will automatically unseat the valve and retain the latter in its unseated position against the stop 23 during the operation of the drill for venting of the crank case through the passages as before. Should the tool be stopped in this inverted position, the ball valve will close by gravity and prevent any lubricant leaking out of the case through the vent passages.

When the drill is held in a position with the drill bit 5 and crank shaft 9 horizontal, the end journal 10 will be likewise disposed, and the valve 22 will automatically seat by gravity should the crank shaft be stopped with the tube 17 above the axis of the shaft. Starting the drill with the crank shaft in this position, the valve 22 will be automatically unseated to open the vent by centrifugal forces set up on the rotation of the crank shaft. Should the crank shaft be stopped while the tool is held in this horizontal position with the tube 17 below the axis of the shaft, the ball valve will automatically unseat by gravity, and in starting the drill from this position .of the tube 17, centrifugal forces set up on the rotation of the crank shaft will cooperate with gravity to hold the valve 22 open to vent the crank case.

Should the drill be held in any position at an angle, either up or down, to the several specified. positions mentioned, the valve 22 will become automatically unseated either by gravity or centrifugal forces, depending on whether the tube 17 extends upward or downward, as will be apparent; centrifugal forces, however, playing an important part in either automatically unseating the valve or co-operating with gravity to retain the valve unseated during the operation of the tool should the crank shaft be started from a position with the valve'initially opened by gravity. The lubricant in the crank case is ap lied to the moving parts by a splash met 10d. This has slow moving properties and, beingheavier than the air, is thrown from the venting valve during the rotation of the crank shaft, so that none of it is carried out with the escaping air.

The tool cannot'be completely filled or packed with grease, so working in an up rightposition there is a tendency for the lubricant to accumulate at the bottom of the crank case, leaving the upper connecting rod bearing dry. The air current created by our vent device moves toward the top of the case carrying lubricant toward the upper connecting rod bearing and crank journal 10, keeping them lubricated. The tube 17 being inclined allows the ball valve 22 to close by gravity when the tool is inverted and idle, thus keeping lubricant from leaking out of the vent. The particular construction described is Well adapted to tools of the character employing counterweights on their crank shafts, and thus makes our invention practical with tools of a smaller size than shown and described in our said copending application Serial No. 673,469.

While we have shown and described herein in detail a form of air venting means of our invention, it is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of our invention.

e claim as our invention:

1. In a piston actuated pneumatic tool, the combination with a crank case, of a crank shaft therein, a counter-weight in said case and fixed to said shaft, and means including a valve for venting the crank case through the counter-weight and crank shaft, said valve being carried by the shaft and being opened by centrifugal forces set up on rotation of the crank shaft.

2. In a piston actuated pneumatic tool, the combination with a crank case, of a crank shaft therein, a counter-weight in said case and fixed to said shaft, means including an, air outlet passage conjointly formed in the counter-weight and crank shaft for venting the crank case, and a valve carried by the counter-weight for controlling said passa e, said valve being opened by centrifu al orces set up on rotation of the crank s aft.

3. In a piston actuated pneumatic tool,

the combination with av crank case, of a crank shaft therein, a counter-wei ht in said case and fixed to said shaft, sai shaft and weight having a conjointly formed air outlet passage for venting the crank case, a tubular member fixed to the counterweight at the passage therein and opening into the same, said member havin a valve seat therein, and a valve in sai tubular jointly formed in the end journal and counter-weight for venting the crank case, a tubular member opening into said passage and secured to the counter-weight be tween the same and the connecting rod, said tubular member having a valve seat therein and being disposed at an inclination to the axis of said shaft, and a valve on said tubular member and being opened by centrifugal forces set up on rotatlon of said crank shaft.

In testimony that we claim the foregoing as our invention,- we aflix our signatures, this 5th day of November, 1923.

AXEL LEVEDAHL. REINHOLD A. NORLING. 

